The DNA damage response in DNA -dependent protein kinase-deficient SCID mouse cells: Replication protein A hyperphosphorylation and p53 induction

Laura M. Fried, Constantinos Koumenis, Scott R. Peterson, Susannah L. Green, Pierre Van Zijl, Joan Allalunis-Turner, David J. Chen, Richard Fishel, Amato J. Giaccia, J. Martin Brown, Cordula U. Kirchgessner

Research output: Contribution to journalArticle

89 Scopus citations

Abstract

Severe combined immunodeficient (SCID) mice display an increased sensitivity to ionizing radiation compared with the parental, C.B-17, strain due to a deficiency in DNA double-strand break repair. The catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) has previously been identified as a strong candidate for the SCID gene. DNA-PK phosphorylates many proteins in vitro, including p53 and replication protein A (RPA), two proteins involved in the response of cells to DNA damage. To determine whether p53 and RPA are also substrates of DNA-PK in vivo following DNA damage, we compared the response of SCID and MO59J (human DNA-PKcs-deficient glioblastoma) cells with their respective wild-type parents following ionizing radiation. Our findings indicate that (i) p53 levels are increased in SCID cells following ionizing radiation, and (ii) RPA p34 is hyperphosphorylated in both SCID cells and MO59J cells following ionizing radiation. The hyperphosphorylation of RPA p34 in vivo is concordant with a decrease in the binding of RPA to single-stranded DNA in crude extracts derived from both C.B-17 and SCID cells. These results suggest that DNA-PK is not the only kinase capable of phosphorylating RPA. We conclude that the DNA damage response involving p53 and RPA is not associated with the defect in DNA repair in SCID cells and that the physiological substrate(s) for DNA-PK essential for DNA repair has not yet been identified.

Original languageEnglish (US)
Pages (from-to)13825-13830
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume93
Issue number24
DOIs
StatePublished - Nov 26 1996

Keywords

  • Ataxia telangiectasia
  • Ionizing radiation
  • MO59J

ASJC Scopus subject areas

  • General

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    Fried, L. M., Koumenis, C., Peterson, S. R., Green, S. L., Van Zijl, P., Allalunis-Turner, J., Chen, D. J., Fishel, R., Giaccia, A. J., Brown, J. M., & Kirchgessner, C. U. (1996). The DNA damage response in DNA -dependent protein kinase-deficient SCID mouse cells: Replication protein A hyperphosphorylation and p53 induction. Proceedings of the National Academy of Sciences of the United States of America, 93(24), 13825-13830. https://doi.org/10.1073/pnas.93.24.13825